THE TRANS-AMAZON DRILLING PROJECT: THE CENOZOIC EVOLUTION OF THE AMAZON’S CLIMATE, FLUVIAL SYSTEM, AND FORESTS (Invited Presentation)

The history of the Amazon region, including the evolution of its fluvial system, climate, and forests has intrigued scientists for centuries. The Amazon forest biome hosts the highest biodiversity in the world – a product of a complex landscape and dynamic geologic and climatic processes across space and through time. Yet despite extensive study over many decades, critical aspects of how biotic diversification is influenced by the evolution of the physical landscape are not well constrained, interpretations of several key aspects of Cenozoic landscape history are controversial, and some intervals of geologic time are poorly documented. The Trans-Amazon Drilling Project (TADP) aims to address these issues by recovering the first long continuous drill cores for scientific study from major basins of the Amazon. These cores span substantive portions of the Cenozoic, enabling a reconstruction of the evolutionary history of climate, the river, and the forests through state-of-the-art application of geochronologic, geochemical, geophysical, and biotic analyses of the sedimentary record. TADP is drilling in the Acre Basin in the west and the Marajó Basin in the east, supplemented by donated drill cores from Potash, Inc from the Amazonas Basin in the center. These three sites span nearly 4,000 km from the distal Andean foreland basin to the mouth of the Amazon River.

Sedimentary sequences from the three sites are characteristic of fluvial systems and include a variety of facies (e.g. flood plain, channel, point bar). We present data from the three sites, including: 1) the initial core descriptions and logging of a 923 m drilled sequence from the Acre Basin that possibly extends into the mid-Miocene; 2) preliminary U-Pb detrital zircon measurements, pollen, and luminescence measurements from the >400 m core from the Amazonas Basin, which at depth contains several pollen taxa very different from those of the contemporary rainforest and that may be Cretaceous in age; and 3) the eastern Marajó Basin, where drilling commenced in May 2024, with unconsolidated sands common in the uppermost ~70m, followed below by sandy layers that alternate with mudstone units, some rich in plant remains. Additional results will be forthcoming by September.